The goal of this program is to improve population health by helping clinicians and their patients address the challenges of individualizing the treatment of breast cancer. Projects 1 and 2 are observational studies that will examine patient and clinician factors associated with locoregional (PI) and systemic therapy (P2). Project 3 will perform a randomized controlled trial of an online decision tool to improve decision quality for patients newly diagnosed with breast cancer. The goal of the Communication and Dissemination Core (Core C) is to translate key research findings into personally relevant messages for patients and clinicians. The University of Michigan's Center for Health Communications Research, an NCI Center of Excellence in Cancer Communications Research, will serve as the backbone for this Core. The first set of Core aims relate to the online patient decision tool that will be tested in P3. Aim 1 Revise and expand ah existing prototype to create a comprehensive patient decision tool. Aim 2 Deploy the comprehensive decision tool as part of the Project 3 randomized controlled trial. Aim 3 Upon completion of the Project 3 trial, revise the decision tool for future dissemination. The second set of Core aims focuses on translating findings from P1 and P2 into tools for clinicians. To do this, we will create a